Also, don't let the midwives bully you into Exclusively breast feeding if she's not latching well.
My first son, Finn, nearly died at 24 hours old because he wasn't eating, and the midwives made my missus feel like gooseberry fool because we wanted to bottle feed instead, just to get
something in him.
Same thing happened when Oscar was born, he was latching, but not getting anything out because he's got a slight tongue tie.
I told the midwives to stick it and went and found the cupboard they kept the mini formula bottles in.
If your missus is adamant about breast feeding but it's not happening, just keep an eye on her as she might start feeling that she's "failed" etc. Keep her reassured that growing the baby and giving birth was phenomenally amazing as it is, it's ok to go to formula, she hasn't failed at all